Particle Edit pushing hair into mesh
I believe that this is because of two reasons.


You'll want to increase the Draw Path Steps (should match particle Steps in particle settings for view port hair to match rendered results) to add more detail while you comb. Draw Path Steps is found in the Tools Panel while in Particle Edit* mode.
Make sure that Deflect Emitter is on in the tool panel while in
particle edit mode and set it where the hair no longer collides.